Oral bacteria linked to the development and progression of oesophageal cancer

Researchers from the Kumamoto University, Japan, were prompted by previous studies* to conduct a study on the role that a type of oral bacterium called Fusobacterium nucleatum has in the development and progression of oesophageal cancer.

Fusobacterium nucleatum is a pathogenic oral bacterium that is well known as a gum disease bug commonly found in dental plaque and periodontal lesions.

Current research shows that F. nucleatum plays a significant role in the development of periodontal disease. It is also associated with invasive infections of the head, neck, chest, lungs, liver and abdomen, and can act as a “bridge” for other late-arrival bacterial organisms to our tooth surfaces and gum tissue. Of note, F. nucleatum has the deceptive ability to deregulate our immune response, as well as secrete specialised proteins called chemokines, which are known to promote interaction between cancer cells.

In the first stage of the Japanese study, researchers used a real-time laboratory analysis technique (QRT PCR) to assess DNA from the cancer tissue of 325 patients. All of these patients underwent surgery to have their oesophageal cancer removed at Kumamoto University Hospital.

The researchers detected and identified the F.nucleatum bacterium DNA in the cancer tissue of 74 patients of the test group, or about 23%. They found that F.nucleatum DNA positivity was significantly associated with the stage (or size) of the tumour, but not with other factors such as age, gender, tobacco use, alcohol use or tumour location.

In the next stage of the study, the researchers made a comparison of the post-surgery survival time of the patients who tested positive for F.nucleatum with those who tested negative. Their findings showed that patients with F.nucleatum present in their cancer tissue had a much shorter survival time as well as more aggressive tumour behaviour (via activation of chemokines).

Further comparative analysis also showed significantly higher levels of F.nucleatum present in cancerous tissue as opposed to normal tissue.

Lead author, Professor Hideo Baba reported, “This study suggested that the oral cavity bacterium F. nucleatum may be involved in the development and progression of esophageal cancer via chemokines”.

Further research is still needed to determine how the F. nucleam bacterium interacts with the development and progression of oesophageal cancer. But given its reputation so far, it is definitely one oral bacterium that we should best avoid through regular brushing, flossing and dental check-ups.

* F.nucleatum has previously been detected by researchers in colon cancer tissue, and the findings show that the bacterium may influence the development of colorectal cancer.
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A study regarding the effects of chewing gum on oral bacteria was conducted by a team of Dutch researchers at the University of Groningen, Netherlands in early 2015. It’s not one to forget. Here’s a recap:

Typically, tooth-brushing, flossing and mouth-washing are considered to be the main ways to remove bacteria from your teeth, tongue and gums. But the Dutch researchers set out to test the hypothesis that chewing gum could also contribute to oral health maintenance.

The research team had volunteers chew gum for up to 10 minutes. Then, the chewed gum was tested for bacteria and colony forming units.

The results were astounding.

Via scanning electron microscopy, the researchers could visually identify bacteria trapped in the gum (see pic). In each piece of gum, around 100 million bacteria were detected. In comparison, tooth-brushing and flossing removed a similar amount of bacteria.

Chewing one piece of gum also reduced about 10% of bacteria in saliva.

The Dutch research team concluded that chewing gum regularly helps to reduce your harmful oral bacteria load significantly. Their findings may promote the development of chewing gum that selectively targets oral disease-related bacteria for better oral health in the future. .

For the time being though, current brands of chewing gum are no substitute for regular tooth-brushing and flossing to maintain your oral health. However, if you are not in a position to brush or floss (e.g. at work), then drinking water and chewing some gum may help reduce your oral bacteria load during the day.